Vitamin D (calciferol)
.jpg)
Vitamin D group formed under the action of ultraviolet radiation in the tissues of animals and plants from sterols.
For vitamin D include:
Vitamin D2 - ergocalciferol; isolated from yeast, it is a provitamin ergosterol;
Vitamin D3 - cholecalciferol, isolated from animal tissues, its provitamin - 7-dehydrocholesterol;
Vitamin D4 - 22, 23-dihydro-ergocalciferol;
Vitamin D5 - 24-etilholekaltsiferol (sitokaltsiferol) isolated from the oils of wheat;
Vitamin D6 - 22-digidroetilkaltsiferol (stigma-calciferol).
Today, vitamin D is called the two vitamins - D2 and D3 - cholecalciferol and ergocalciferol - these are the crystals colorless and odorless, resistant to high temperatures. These vitamins are fat soluble, ie, soluble in fats and organic compounds, and insoluble in water.
Active vitamin D is expressed in international units (ME):
1 IU = 0.025 mcg cholecalciferol, 40 IU = 1 mcg cholecalciferol
Animal sources:
egg yolk, butter, cheese, fish oil, eggs, dairy products
However, in practice, milk and dairy products do not always contain vitamin D, or contains only trace (minor) number (for example, 100 grams of cow's milk contains only 0.05 milligrams of vitamin D), so their consumption is, unfortunately, can not guarantee the coverage of our the need for this vitamin. In addition, the milk contains large amounts of phosphorus, which prevents the absorption of vitamin D.
Plant sources:
alfalfa, horsetail, nettle, parsley
Synthesis in the body:
cholecalciferol is formed in the skin by ultraviolet rays of sunlight
Provided that the body gets enough ultraviolet radiation, the need for vitamin D is compensated in full. However, the amount of vitamin D, synthesized under the action of sunlight depends on such factors as:
wavelength of light (the most effective medium wave spectrum, which we have in the morning and at sunset);
the original skin pigmentation (darker skin, the less vitamin D produced by sunlight);
age (aging skin loses its ability to synthesize vitamin D);
atmospheric pollution (industrial emissions and dust will not miss the range of ultraviolet rays, potentiating the synthesis of vitamin D).
Action
The main function of vitamin D - to ensure proper growth and bone development, the prevention of rickets and osteoporosis. It regulates mineral metabolism and promotes the deposition of calcium in bone and dentin, thus preventing osteomalacia (softening) of bones.
Vitamin D affects the overall metabolism in the metabolism of Ca2 + and phosphate (NRO2-4). First of all, it stimulates the intestinal absorption of calcium, phosphate and magnesium. An important effect of vitamin during this process is to increase the permeability of the intestinal epithelium for Ca2 + and R.
Vitamin D is unique - it is the only vitamin that acts as a vitamin, and as a hormone. As it supports vitamin levels of inorganic P and Ca in plasma above the threshold and increases absorption of calcium in the small intestine.
As a hormone acting active metabolite of vitamin D - 1,25-dioksiholekatsiferol formed in the kidneys. It affects the cells of the intestines, kidneys and muscles: in the gut stimulate the production of carrier protein required for the transport of calcium in the kidneys and muscles increases the reabsorption of Ca + +.
He warns muscle weakness, improves the immune system (the level of vitamin D in the blood is one of the criteria for evaluating life expectancy of AIDS patients), it is necessary for the functioning of the thyroid gland and normal blood clotting.
External use of vitamin D3 for psoriasis reduces the characteristic scaly skin.
Vitamin D3 is involved in regulation of blood pressure (particularly in pregnant women with hypertension) and heart rate.
Vitamin D inhibits the growth of cancer cells and that makes it effective in the prevention and treatment of breast, ovarian, prostate, brain, and leukemia.
Daily requirement Age (years) - mcg
0-0,5 - 10
0,5-1 - 10
3.1 - 10
4.6 - 2.5
7-10 - 2.5
Men:
11-14 - 2,5
15-18 - 2,5
19-59 - 2,5
60-74 - 2,5
Over 75
Women:
11-14 - 2,5
15-18 - 2,5
19-59 -2,5
60-74 - 2,5
Older than 75 - 2,5
Pregnant -10
Breastfeeding -10
Increased need for vitamin D is higher in people experiencing a lack of UV radiation:
living at high latitudes,
inhabitants of regions with high air pollution,
working the night shift or just a nocturnal,
bedridden patients who have never been outdoors.
People with darker skin (Negroid race, tanned people) synthesis of vitamin D in the skin decreases.
The same is true of the elderly (they have the ability to convert vitamin D into provitamins reduced by half) and those who adhere to a vegetarian diet, or consume insufficient amount of fat.
Adversely affect the absorption of vitamin D for intestinal disorders, liver and gall bladder dysfunction.
Pregnant and lactating women need for vitamin D is increased, because require additional quantity to prevent rickets in children.
Symptoms of hypovitaminosis
The main sign of vitamin D deficiency is rickets, and softening of bones (osteomalacia).
Milder forms of vitamin D deficiency manifest symptoms such as:
loss of appetite, weight loss,
burning sensation in the mouth and throat,
insomnia,
impairment.
